Intoxication is not a defence to a crime as such, but where a person is intoxicated through drink or drugs and commits a crime, the level of intoxication may be such as to prevent the defendant forming the necessary mens rea of the crime. Public policy plays a strong factor in ascertaining whether the defendant's intoxication may be used by a defendant to negate the mens rea of a crime. It is obviously not in the public interest for criminals to escape liability simply by asserting they were so drunk they did not know what they were doing. This is often seen as an aggravating factor rather than a mitigating factor, particularly where the defendant put himself in that position.

The law has formulated various rules of uncertain ambit in seeking to strike the balance between on the one hand, imposing criminal liability on a party who did not have the mental element of the crime and on the other, protecting the public from those who deliberately put themselves in a postion where they are unable to control their actions. For this reason the law draws a distinction between voluntary intoxication and involuntary intoxication. The law is generally more accomodating to those who have not voluntarily put themselves into an intoxicated state.

Involuntary intoxication

The most obvious example of involuntary intoxication is where a person has had their food or drink spiked without their knowledge. However, it may also cover where a particular drug has an unexpected result to that anticipated:

However, in the case of R vKingston, the House of Lords held there was no such defence. Only where the defendant could be shown to lack the mens rea of the offence due to his intoxicated state could he escape criminal sanction. Thus where drink or drug removes the inhibitions of the defendant so that they may do things which they would not do when they are sober, they nevertheless often have the mens rea of the crime. The law will not excuse this behaviour even where the defendant had been drugged by the fraud of another:

Where the defendant has voluntarily put themselves in the position of being intoxicated to the extent that they are not capable of forming the mental element of the crime the law is less forgiving. The law draws a distinction between crimes of basic intent and crimes of specific intent. This distinction was drawn in DPP v Beard and affirmed in DPP v Majewski.

No explanation of the terms is entirely satisfactory and do not accurately cover the offences which have been categorised as either basic intent crimes or specific intent crimes. This was most noticeable in:

The confusion surrounding these terms has attracted criticism from the Law Commission who have recommended the terms should be discarded and replaced with an integral fault element.

Crimes of specific intent

Crimes of specific intent have sometimes been stated to include crimes where the offence can only be committed intentionally ie where recklessness will not suffice eg murder, s.18 wounding and GBH. (NB this definition was doubted by the Court of Appeal in R v Heard, although was given by Lord Diplock in Caldwell). Another definition often used is where the offence requires an ulterior intent ie one which requires proof of an intent which goes beyond the prohibited act eg criminal damage with intent to endanger life. This definition was preferred in Heard and was the dissenting opinion by Lord Edmund Davies and Lord Wilberforce in Caldwell. However, the difficulty with this definition is that it does not cover murder which has been categorised as a crime of specific intent.

Crimes which have been categorised as being 'specific intent' crimes include:

Where a crime is categorised as being one of specific intent, the defendant is allowed to rely on their intoxication to demonstrate that they lacked the mens rea of the offence. This is subject to the caveat that a drunken intent is nevertheless an intent:

Where a defendant's intoxication is voluntary and the crime is one of basic intent, the defendant is not permitted to rely on their intoxicated state to indicate that they lack the mens rea of the crime.

Other matters relating to intoxication

Intoxication and Dutch Courage

Where a person forms the intention to commit a crime and then drinks in order to enable them to carryout the crime, they can not then claim the intoxication prevented them from forming the mens rea:

Where a defendant is labouring under a mistaken belief that they are under attack and acting in self-defence, they can not rely on such mistaken belief where it was induced by voluntary intoxication. This applies to crimes of both basic intent and specific intent.